DNA-CTMA functionalized GaN surfaces for NO₂ gas sensor at room temperature under UV illumination

Considering the power consumption and safety risks in the presence of combustible gases, sensor operation at room temperature (RT∼28 °C) has drawn much interest in recent days. Different strategies have been found to meet the effective sensor performance at RT. Here, we report a riveting combination of DNA‒CTMA/GaN (DGaN) hybrid structure for high-sensitive NO₂ gas sensor at RT. The surface modifications are caused by the functional groups of DNA‒CTMA interactions with GaN. The XPS studies reveal that the native oxides of GaN surface are binding with the functional groups of DNA‒CTMA. The DGaN hybrid structure display higher response to various concentrations (100–10 ppm) of NO₂ compared to the pristine GaN film. The effect of UV illumination on NO₂ gas sensing performance of DGaN is also manifested, and the response of the sensor is enhanced under UV illumination in comparison with those of dark condition. From our observations, the amine groups and the negatively charged hydroxyl groups in DNA‒CTMA helps for the higher response of gas sensor by the hybrid structure which makes them a good candidate for high-response NO₂ gas sensors at RT.